The long-term goal of these studies has been to effect an improvement in the duration and quality of survival following heart allotransplantation. Various aspects have been explored, including the physiology and pharmacology of canine heart replantation, heart storage techniques, immunosuppressive regimens in canine heart allotransplantation, and refinements in surgical techniques. During the past year much investigative effort has been directed toward perfecting a computer program to assess physiological and pharmacological parameters of function of canine heart transplants. In the coming year research goals include: (1) the completion of the computerized assessment of various aspects of cardiac function after heart transplantation. A variety of drugs will be utilized in the computer studies, with an eye to discerning their effects on pump function and muscle function indices. (2) further study of cell membrane lipid changes in the hypothermic heart relative to heart storage. All studies will include a comparsion of active hibernators (marmots) with non-hibernators (dogs). The effects of administration of a fat emulsion (high in unsaturated fatty acids) and exposure to cool-warm cycling will be examined in these animals. (3) Compilation of all outstanding work accomplished during the term of the present support.